This invention relates to blood pumps for cardiac support, and is more particularly concerned with an expandible and contractible member to be placed within the ventricular chamber of a patient's heart and which expands and contracts on diastole and systole, respectively, to assist movement of the patients blood into and out of the left ventricle. The invention is also concerned with an endocardial left ventricle assist device or LVAD which does not rely on pumping of air or other fluids to open or inflate the device.
There are pathological conditions that affect the circulatory system, and in particular the heart tissues, which can impair the ability of the heart to pump a normal volume of blood. Injury or disease affecting the muscular tissues of the left ventricle can result in the heart only pumping weakly, or not contracting fully during systole. In order to provide a normal blood flow while a patient's heart is given a chance to heal or improve, there have been several proposals for blood pumps, and in particular intraventricular pumping aids, to help push the patient's blood out of the left ventricle during contraction or systole. Ventricular assist balloon devices, for example, employ a balloon in either the aorta or the left ventricle that inflate in synchronism with the heart's rhythm to squeeze the blood out of the heart and along the aorta. These devices depend on supplying a gas or fluid to inflate and deflate the balloon, and thus can create a risk of injecting gas bubbles directly into the aortic blood. Moreover, these devices are unable to sufficiently augment blood flow in a severely failing hear. Other devices employ an impeller to pump the blood, which can cause hemolysis, among other complications.
It is desired to employ an intracardial LVAD that uses simple rhythmic mechanical motion to drive the pumping mechanism that is placed within the patient's left ventricular cavity to provide a controllable, reliable system to increase blood flow through the patient's system and to compensate for the weakness in the patient's own heart, and to continue the enhanced blood flow during the time of cardiac distress until the patient's condition improves.